**5. Discussion**

This paper formulates a thesis that requirements related to regulation, protection and integration of power generation units and battery storage system with power systems have an impact on the planning and operation strategies of the VPP. After a comprehensive study of the current grid codes, standards and papers, three topics were selected and highlighted in the VPP:


Mentioned issues were investigated based on the real VPP project. The results obtained are distinctive and related to the investigated localization of the VPP, however, the proposed test method and results obtained can be treated more generally. In order to determine indicated aspects, a few test methods using Matlab simulation have been implemented, combining actual load demand measurements with data generated as a prerequisite for simulation and direct analysis of actual measurements. Application of the proposed method to the real case study of the VPP allowed to formulate several observations related to the operational capabilities of the VPP and technical requirements related to the integration of the DER and ESS with the utility grid:


• Representation of the grid covered by the VPP using a simulation model, which is complemented by actual measurements, provides extended opportunities for research into the choice of strategy for planning and operating a VPP. Presented results allowed to determine the impact of power changes of energy storage system or hydropower plant on the reduction of load on lines and transformers and on voltage changes. It can be used to create energy system services provided by VPP.

Obtained results constitute the influence of the technical requirements for DER and ESS integration with the power grid on the VPP operational condition.
